Lawmate Mods - Revision history

Ivc: /* Lawmate 2.4GHz transmitter */

2014-03-25T15:50:22Z

Lawmate 2.4GHz transmitter

← Older revision		Revision as of 15:50, 25 March 2014
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	* [http://beta.ivc.no/rc_helicopter/lawmate_transmitter_lm-240500-lm.pdf Lawmate LM24050-LM transmitter manual] - pdf		* [http://beta.ivc.no/rc_helicopter/lawmate_transmitter_lm-240500-lm.pdf Lawmate LM24050-LM transmitter manual] - pdf

			The supplied cable has the following connectors/housings:

			* To unit: JST-SH Micro 1.00 pitch 4-pin connector - SHR-04V-S-B
			* To aux: Molex PicoBlade 1.25 pitch 4-pin connector - 51021-0300

	Frequencies (Channel, dip-switch, frequency):		Frequencies (Channel, dip-switch, frequency):

	* CH1 On-On-On 2410MHz		* CH1 On-On-On 2410MHz
	* CH2 Off-On-On 2430MHz		* CH2 Off-On-On 2430MHz

Ivc at 13:40, 21 January 2014

2014-01-21T13:40:35Z

← Older revision		Revision as of 13:40, 21 January 2014
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	== Lawmate 2.4GHz receiver ==		== Lawmate 2.4GHz receiver ==
	[[Image:Lawmate_24ghz_receiver.jpg\|400px\|right]]The RX-2460CK receiver contains a Comtech FM2400RTIM8 module with a relatively good receiver sensitivity, -95dBm [http://forum.tsebi.com/viewtopic.php?p=1158#p1158]. The signal input is a regular female threaded outside and ~~pin~~-socket inside SMA connector [http://www.nghobbies.com/cart/images/products/lawmate/2460_4.JPG].		[[Image:Lawmate_24ghz_receiver.jpg\|400px\|right]]The RX-2460CK receiver contains a Comtech FM2400RTIM8 module with a relatively good receiver sensitivity, -95dBm [http://forum.tsebi.com/viewtopic.php?p=1158#p1158]. The signal input is a regular female threaded outside and center-socket inside SMA connector [http://www.nghobbies.com/cart/images/products/lawmate/2460_4.JPG].

	* [http://beta.ivc.no/rc_helicopter/lawmate_receiver_lmrx60.pdf Lawmate RX-2460CK receiver manual] - pdf		* [http://beta.ivc.no/rc_helicopter/lawmate_receiver_lmrx60.pdf Lawmate RX-2460CK receiver manual] - pdf

Ivc: /* Narrower band filter */

2013-05-06T08:19:43Z

Narrower band filter

← Older revision		Revision as of 08:19, 6 May 2013
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	=== Narrower band filter ===		=== Narrower band filter ===
	[[Image:Lawmate_24ghz_receiver_saw_filter.jpg\|400px\|right]]The default ComTech module uses a 20MHz or 27MHz SAW ~~(Surface Acoustic Wave)~~ IF filter which is normally used for receiving a signal from a satellite, but for terrestrial use a narrower bandpass filter is preferred to limit the near-band noise and thus improving the signal-to-noise ratio.		[[Image:Lawmate_24ghz_receiver_saw_filter.jpg\|400px\|right]]The default ComTech module uses a 20MHz or 27MHz SAW IF filter which is normally used for receiving a signal from a satellite, but for terrestrial use a narrower bandpass filter is preferred to limit the near-band noise and thus improving the signal-to-noise ratio.

	By removing the default F480-2 filter and replace it with a new ECS-D480A bandpass filter, should result in a gain in signal-to-noise of be about 1.4dB [http://fpvlab.com/forums/showthread.php?1090-Lawmate-2.4GHz-Tuned-Video-Receiver&p=16556&viewfull=1#post16556].		By removing the default F480-2 filter and replace it with a new ECS-D480A bandpass filter, should result in a gain in signal-to-noise of be about 1.4dB [http://fpvlab.com/forums/showthread.php?1090-Lawmate-2.4GHz-Tuned-Video-Receiver&p=16556&viewfull=1#post16556].

Ivc: /* Lawmate 2.4GHz receiver */

2013-05-06T08:18:34Z

Lawmate 2.4GHz receiver

← Older revision		Revision as of 08:18, 6 May 2013
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	* CH4 #4 2470MHz		* CH4 #4 2470MHz

	Switch B:		Switch B (always use this with Lawmate tx):
	* CH1 #1 2410MHz		* CH1 #1 2410MHz
	* CH2 #2 2430MHz		* CH2 #2 2430MHz

Ivc: /* RSSI output */

2013-02-05T14:00:56Z

RSSI output

← Older revision		Revision as of 14:00, 5 February 2013
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	=== RSSI output ===		=== RSSI output ===
	[[Image:Lawmate_24ghz_receiver_rssi.jpg\|400px\|right]]The RSSI (Received signal strength indication) output is an analog voltage changing reflecting the relative strength of the received signal. By using multiple receivers a diversity switcher could dynamically pick the one with the best signal.		[[Image:Lawmate_24ghz_receiver_rssi.jpg\|400px\|right]] [[Image:Lawmate_24ghz_receiver_rssi_connector.jpg\|400px\|right]]The RSSI (Received signal strength indication) output is an analog voltage changing reflecting the relative strength of the received signal. By using multiple receivers a diversity switcher could dynamically pick the one with the best signal.

	The image below shows pin 9 which is the RSSI output of the receiver module.		The image below shows pin 9 which is the RSSI output of the receiver module.

Ivc: /* Lawmate 2.4GHz transmitter */

2013-02-05T13:53:40Z

Lawmate 2.4GHz transmitter

← Older revision		Revision as of 13:53, 5 February 2013
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	* CH7 On-Off-Off 2490MHz		* CH7 On-Off-Off 2490MHz
	* CH8 Off-Off-Off 2510MHz - outside ISM band		* CH8 Off-Off-Off 2510MHz - outside ISM band

			The fourth DIP-switch does not do anything, AFAIK.

	=== Thermal mod ===		=== Thermal mod ===

Ivc: /* Thermal mod */

2013-02-05T01:05:17Z

Thermal mod

← Older revision		Revision as of 01:05, 5 February 2013
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	By opening and removing all the excessive solder, a new thermal path can be built into the casing. I used three small 0.75mm copper pieces soldered together. The pieces were soldered to the casing and a thin layer of silver-based (Arctic Silver 5) thermal paste was applied between the board and the copper pieces.		By opening and removing all the excessive solder, a new thermal path can be built into the casing. I used three small 0.75mm copper pieces soldered together. The pieces were soldered to the casing and a thin layer of silver-based (Arctic Silver 5) thermal paste was applied between the board and the copper pieces.

			Lastly, move the stock heatsink from the top tin case to the bottom case where the heat now dissipates. The DIP-switches might be covered up, thus either change the channel to the desired frequency now or cut away a small piece of aluminum to expose the switches.

	It is also essential to have a tuned antenna because badly tuned VSWR match means warmer vtx, better VSWR match means cooler vtx (less power reflected back to the amplifier) [http://fpvlab.com/forums/showthread.php?5689-Lawmate-VTX-cooling-mods-from-TBS-site&p=97294&viewfull=1#post97294].		It is also essential to have a tuned antenna because badly tuned VSWR match means warmer vtx, better VSWR match means cooler vtx (less power reflected back to the amplifier) [http://fpvlab.com/forums/showthread.php?5689-Lawmate-VTX-cooling-mods-from-TBS-site&p=97294&viewfull=1#post97294].

Ivc: /* Reinforced connector */

2013-02-05T01:00:32Z

Reinforced connector

← Older revision		Revision as of 01:00, 5 February 2013
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	The SMA connector on the stock unit is supported by the center pin and a fairly brittle solder spot to the tin case. To improve the support add a rim of solder around the connector. Heat the entire connector to avoid weak cold joints.		The SMA connector on the stock unit is supported by the center pin and a fairly brittle solder spot to the tin case. To improve the support add a rim of solder around the connector. Heat the entire connector to avoid weak cold joints.

	Make sure to take into account gap on the top case still fits on the bottom case.		Make sure to take into account that the SMA connector gap on the top case still fits on the bottom case.

	== Lawmate 2.4GHz receiver ==		== Lawmate 2.4GHz receiver ==

Ivc: /* Reinforced connector */

2013-02-05T00:59:01Z

Reinforced connector

← Older revision		Revision as of 00:59, 5 February 2013
Line 33:		Line 33:

	=== Reinforced connector ===		=== Reinforced connector ===
	The SMA connector on the stock unit is supported by the center pin and a fairly brittle solder spot to the case. To improve the support add a rim of solder around the ~~whole~~ connector ~~to reinforce~~ the connector ~~support~~.		The SMA connector on the stock unit is supported by the center pin and a fairly brittle solder spot to the tin case. To improve the support add a rim of solder around the connector. Heat the entire connector to avoid weak cold joints.

	Make sure to take into account gap on the top case still fits on the bottom case.		Make sure to take into account gap on the top case still fits on the bottom case.

Ivc: /* Video impedance correcton */

2013-02-05T00:55:50Z

Video impedance correcton

← Older revision		Revision as of 00:55, 5 February 2013
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	By adding a small 100 Ohm resistor in parallel to ground, the input impedance will drop to 1/(1/342+1/100) = 77 Ohm.		By adding a small 100 Ohm resistor in parallel to ground, the input impedance will drop to 1/(1/342+1/100) = 77 Ohm.

			=== Reinforced connector ===
			The SMA connector on the stock unit is supported by the center pin and a fairly brittle solder spot to the case. To improve the support add a rim of solder around the whole connector to reinforce the connector support.

			Make sure to take into account gap on the top case still fits on the bottom case.

	== Lawmate 2.4GHz receiver ==		== Lawmate 2.4GHz receiver ==